The Multi-User Database Environment

A multi-user database is a database that many users can access at the same time. These users typically employ computer terminals online to a central computer in which the database is stored. There may be a few users (for example, fifteen clerks in a billing office) or a few thousand users (for example, airline reservation clerks and travel agents using an online reservation system). We will consider the multi-user environment in the context of a company-wide database, but you should know that some multi-user databases are used only by small groups within a company whereas others are used by many people in many different companies. Within a company, functional departments groups of employees headed by a manager are responsible for certain tasks. Each department is judged by how effectively and efficiently it accomplishes the tasks it is assigned. Sometimes the goals of one department conflict with those of another department.

Consider a company that offers intensive two-month training courses in automotive repair. Conflicts might occur, for example, between teachers and salespeople. The salespeople are responsible for enrolling students. Their salaries and bonuses are based on volume. The teachers are responsible for training, and they are judged by the number of students who successfully complete the course. Suppose the salespeople enroll students who do not have the necessary skills or background to complete the course. When students drop out (and demand tuition refunds), the teaching staff may appear to be doing a poor job. On the other hand, suppose the instructional staff were allowed to reject applicants whom it felt were unqualified. Probably a higher proportion of students would complete their training. But the salespeople would complain that their bonuses were being manipulated by an elitist group of teachers. In the evolution of data processing systems, each functional department in a company typically developed its own set of files (called master files), which it periodically updated and from which it retrieved information pertinent to its own particular business needs. No department depended on another one to collect or enter its data. Rather, each department was on its own. Each department felt that it was in control of the data it needed. Even if some departmental goals conflicted with those of another department, at least some territorial boundaries were established regarding data. The database environment is very different from the departmental-file environment. Users collect and share data. Users seldom have absolute control over any data in the database.

Suppose the teaching staff depends on the sales staff to collect data about each student's educational background, reading level, and work schedule. Such data is needed to schedule the student into a class. But because the sales staff does not need the data to close a sale, it may not be careful in collecting it. And the data that salespeople do collect may be unreliable. In frustration, and to ensure it has the data it needs, the teaching staff may establish its own student master files, duplicating much of the data the sales staff collects (or is supposed to collect). As a result, the company has duplicated data in two distinct file processing systems-a poor solution. Data is useful to a company when it is stored in such a way that in addition to satisfying all individual departmental needs it can be used to answer corporate management questions.

Imran Zafar writes articles about computer basics and database management such as and meaning of computer, basics of computer